'-' hyphen is replaced with an underscore, '_'

pipreqs --encoding=utf8 .
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It appears that pipreqs '-' hyphen is getting replaced with an underscore.
Following are the few examples, where pipreqs used an underscore where it should have been '-'
opencv_python==4.5.5.64
marshmallow_enum==1.5.1
python_json_logger==2.0.2
scikit_image==0.19.2
scikit_learn==1.0.2

Start by reproducing the reported `pipreqs --encoding=utf8 .` behavior with imports corresponding to the listed packages. Trace where imported names become requirement names, then verify that packages such as opencv-python, scikit-image, and scikit-learn retain hyphens in the generated requirements output. There is no file or test named in the issue, so add focused coverage for these examples if the project’s test structure allows it.

Written by the indexing model from the issue text.